exhaust manifold gasket
- Thread starter meteorgray
- Start date
Big hammer
Well-known member
No, I put the folded edge against the block.
stevemclark
Senior Member
Torque it evenly from inside to outside 25-35 lbs.Ford Model A specification torque, some venders say 55lbs for their manifolds. Any other ideas?Sealant or not?
meteorgray
Member
I think I will put a thin coat of Permatex Optima High temp
sealant. Good for exhaust headers 750 degrees.
Roger
sealant. Good for exhaust headers 750 degrees.
Roger
nkaminar
Well-known member
The studs and bolts are the same as the ones used on the head. So torque to 55 foot-pounds. The gaskets for the manifold settle in more than the head gasket so re torque after the initial heat. Re torque like you would do with the head, after the initial heat, after 100 miles, etc. Some owners say to loosen the bolts that fasten the exhaust manifold to the intake manifold before you do the torquing.
Ed in Maine
Well-known member
The studs may be the same as the cylinder head but how about the "ears" on the exhaust manifold? I would stay with the published spec.s of 30-35 ft. lbs. and torque them often after installation and driving.
alexiskai
Well-known member
Remember that the point of tightening the nuts on the manifold studs – whatever torque value you're using – is to seal the gaskets. Tightening beyond the force needed to seal your particular gaskets on your particular engine does nothing except put shear stress on the manifold ears.
For perspective, the Remflex gaskets specify 15 ft-lbs.
For perspective, the Remflex gaskets specify 15 ft-lbs.
meteorgray
Member
Hey guys, thanks for all your suggestions and information, very helpful.
Roger
Roger
Bob Bidonde
Well-known member
These slides may help you.
The large washers that clamp the exhaust & intake manifolds are actually cupped to act like springs. The cupped springs take-up thermal expansion of the studs and manifolds so the joints remain tight. The cups open inward. If you torque the cup washers like the cylinder head nuts, you are likely flattening them and defeating their purpose. The cupped washers were originally made from leaf spring material.
My practice is to torque the nuts to 25 to 35 lbs-ft, warm-up the engine to operating temperature, and tighten the manifold nuts just enough to stop any leaks.
The large washers that clamp the exhaust & intake manifolds are actually cupped to act like springs. The cupped springs take-up thermal expansion of the studs and manifolds so the joints remain tight. The cups open inward. If you torque the cup washers like the cylinder head nuts, you are likely flattening them and defeating their purpose. The cupped washers were originally made from leaf spring material.
My practice is to torque the nuts to 25 to 35 lbs-ft, warm-up the engine to operating temperature, and tighten the manifold nuts just enough to stop any leaks.
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Interestingly, I just saw a video the other day by Mr. Shinn who said the A manifold should be tightened from one end to the other (from either end) but not from the center out. Not sure if that's due to the tendency for warping but he specified it's not like a cylinder head.
No argument from me - just passing that along.
D
No argument from me - just passing that along.
D
alexiskai
Well-known member
Correct, it's not like a cylinder head because it's one-dimensional. The bolts are all in a line. Tightening down the line from one end to the other minimizes the bending strain at each joint.
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nkaminar
Well-known member
Katy, The washers do not deflect, they are too stiff. They act like a suspension system and rock to accommodate slightly different thicknesses of the flanges. The concave side should be against the manifolds.
What ever torque you decide to use, tighten the nuts a little at a time so that the manifolds stay flat. And check the torque after an initial heat and after 100 miles or less. You will be surprised by how much the gaskets compress. Don't use the paper gaskets, use only the composite gaskets made up of a copper sandwich. Make re torquing part of your maintenance procedure.
What ever torque you decide to use, tighten the nuts a little at a time so that the manifolds stay flat. And check the torque after an initial heat and after 100 miles or less. You will be surprised by how much the gaskets compress. Don't use the paper gaskets, use only the composite gaskets made up of a copper sandwich. Make re torquing part of your maintenance procedure.
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meteorgray
Member
I did 30lbs starting at 20lbs with 5lb increments. So far no leaks!